High impact information on tscA

• We suggest from these experiments that the product of the tscA gene may be a small chloroplast RNA that acts in trans in the first trans-splicing reaction of psaA [1].
• At least one additional chloroplast locus (tscA) is required for trans-splicing of exons 1 and 2 [1].
• The 0.7 kb region of the chloroplast genome that is sufficient to rescue tscA function has been subjected to insertion mutagenesis, showing that it does not contain significant open reading frames [1].
• In order to investigate in vivo splicing of group II introns in chloroplasts, we previously have integrated the mitochondrial intron rI1 from the green alga Scenedesmus obliquus into the Chlamydomonas chloroplast tscA gene [2].
• The self-splicing group II intron (rl1) from Scenedesmus obliquus mitochondria together with its 6 bp intron binding site (IBS1) were inserted in the correct and inverse orientation into the chloroplast tscA gene from C.reinhardtii [3].

Biological context of tscA

• As expected, no RNA splicing at all was observed when the intron had an inverted orientation within the tscA gene [3].
• Targetted gene disruption mutants of loci required for photosynthesis, tscA and psaC, were thus obtained [4].
• Only four of these genes (tscA and three reading frames) have not been identified in any other algal cpDNAs and thus may be specific to Chlamydomonas [5].

References